There’s a few ways you can screen lock a mac but I wanted to not just lock the screen also put a message in the login window. Using ScreenLock from and Quiksilver you can quickly launch the lock and then by running the following you can neatly add a message to the login window. sudo defaults write /Library/Preferences/ LoginwindowText “If you need me, call me.” Just do “” to blank it again or ditch the file. Easy!